RTE writes that in ‘Family Tree,’ O’Dowd plays 30-year-old Tom Chadwick who embarks on a journey of self-discovery after his aunt leaves him a mysterious box in her will.

Said O’Dowd of his new project, "It's totally improvised: essentially, you go into each scene with a paragraph of story, but there's no dialogue written down. It's very exciting, but it's hard, I'm not gonna lie.”

"It's a tricky skill to improvise while also getting all that story across, but I'm enjoying it. I have to say, I'm really excited for January because we're bringing in some of the guys who've been in his troupe for so long.”

"It's been all English people up till now, but Fred Willard, Ed Begley Jr and Chris Guest himself come into the show in January, so I can't wait for that."

The show will air in the UK on BBC, but is expected to air in the US on HBO sometime in the spring. However, O’Dowd will be on HBO earlier this year as he reprises his guest role on the critically-acclaimed series ‘Girls.’